This invention pertains to the field of ground fault circuit interrupter devices, and in particular, to a ground fault interrupter device with an indicator lamp.
Ground fault circuit interrupters (GFCIs) are well known in the art. Their intent is and always has been to protect the electrical power user from electrocution when hazardous ground fault currents are present.
Historical problems with these devices include the possibility of line/load miswiring in the field by an installer or the eventual failure of the solenoid driving device, typically a silicon controlled rectifier, which causes the interrupter device to become inoperable while electrical power is still present, even under hazardous ground fault conditions. A variety of methods are used to prevent or attempt to prevent miswiring with varying levels of success. Preventing the problems associated with a defective solenoid driving device is inherently more difficult. Labels and installation instruction sheets have been used to prevent miswiring, but can be ignored by the installer. Solenoid burn-out has been revealed by testing the protective with a test button, but the result of the test can be ignored by the user.
Briefly stated, an AC power line protection device which includes miswiring protection has an indicator lamp which lights when the device is in the tripped condition and turns off when the device is reset. If the device is miswired after having been wired properly, the indicator lamp does not light when the device is tripped, and so provides a supplemental indication of miswiring. The indicator lamp is powered via the hot line bus bar of the interrupting contacts to meet safety standards.
According to an embodiment of the invention, a protection device connected between hot and neutral conductors of an AC power line includes a fault detection circuit including a breaker coil operatively associated with a set of interrupting contacts; the interrupting contacts including a hot bus bar and a neutral bus bar; an indicator lamp circuit including an indicator lamp connected between the hot conductor on a line side of the interrupting contacts and the hot bus bar; and the fault detection circuit being powered from the hot bus bar.
According to an embodiment of the invention, a method for protecting against miswiring a protection device connected between hot and neutral conductors of an AC power line, wherein the device includes an interrupter having two contacts on a hot bus bur connected respectively to line hot and load hot terminals and two contacts on a neutral bus bar connected respectively to line neutral and load neutral terminals, wherein the interrupter opens and closes to electrically disconnect and connect the load hot terminals, respectively, includes the steps of connecting a resistance between the hot conductor on a line side of the interrupter and the hot bus bar; and connecting an indicator in series with the resistance, wherein the indicator indicates if a power source is connected across the line hot and line neutral terminals while the contacts are open.